Vehicle structure with integral node

ABSTRACT

A fluid formed node is provided to connect structure in an automotive vehicle. Another aspect of the present invention includes a method of forming a structural interconnection including the steps of placing a first member, having an internal cavity in a die pressurizing the internal cavity to form a node integral with and protruding from the first member, disposing the node within an aperture of a second member, and coupling the second member to the node.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention pertains generally to structural members and, moreparticularly, to a vehicle structure having an integral node.

In the field of motor vehicle design, it is highly desirable toconstruct a modular vehicle including a subframe adaptable for use witha variety of aesthetically pleasing outer panels. Additionally, the useof extruded tubular sections within the construct of the subframegreatly enhances the strength and durability of the frame withoutdrastically increasing the weight and cost.

Unfortunately, many manufacturers have had difficulty reliablyinterconnecting individual tubular frame components to form adimensionally correct and structurally robust vehicle frame.Accordingly, some manufacturers have implemented separate connectors,called nodes, to facilitate the joining process. The separate nodes aretypically aluminum alloy castings having a plurality of apertures forreceipt of tubular frame components. Due to the relative difficulty ofwelding aluminum alloys, cast nodes are especially prevalent in jointsstructurally interconnecting stamped or extruded aluminum components. Aswould be expected, the use of separate nodes is both costly and timeconsuming. Therefore, a need in the relevant art exists for an apparatusand method for interconnecting structural members.

Accordingly, it is an object of the present invention to provide animproved vehicle body construction exhibiting the advantages of atubular construction without the need for separate connectors such ascast nodes.

It is another object of the present invention to provide a structuralcomponent including an integrally hydroformed node for use in a vehiclestructure having improved strength and dimensional accuracy.

In accordance with the present invention, a fluid formed node isprovided to connect structure in an automotive vehicle. Another aspectof the present invention includes a method of forming a structuralinterconnection including the steps of placing a first member, having aninternal cavity in a die, pressurizing the internal cavity to form anode integral with and protruding from the first member, disposing thenode within an aperture of a second member, and coupling the secondmember to the node.

The node of the present invention is advantageous over conventionalconstruction in that the present invention provides an integrally formedattachment location economically created through the use ofhydroforming. Additionally, structures incorporating the node of thepresent invention exhibit superior dimensional stability and structuralintegrity as compared to the structures previously described. Furtherareas of applicability of the present invention will become apparentfrom the detailed description provided hereinafter. It should beunderstood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are intended forpurposes of illustration only, since various changes and modificationswithin the spirit and scope of the invention will become apparent tothose skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an automotive vehicle skeletal structureshowing the preferred embodiment of a node of the present invention;

FIG. 2 is a fragmentary, exploded perspective view showing the preferredembodiment node;

FIG. 3 is a cross-sectional view showing a first embodiment of anextruded tubular member having an integral flange employed with thepreferred embodiment node;

FIG. 4 is a cross-sectional view showing a second embodiment of anextruded tubular member having two integrally formed flanges employedwith the preferred embodiment node;

FIG. 5 is a cross-sectional view, taken along line 5—5, showing a thirdembodiment of an extrusion employed with the preferred embodiment node;

FIG. 6 is a cross-sectional view of a pair of hydroforming dies havingthe extrusion of FIG. 5 disposed within an internal cavity thereof;

FIG. 7 is a cross-sectional view of a second pair of hydroforming dieshaving a partially deformed extrusion disposed within an internal cavitythereof;

FIG. 8 is a cross-sectional view, taken along line 8—8 of FIG. 2,showing a first member employed with the preferred embodiment node;

FIG. 9 is a another fragmentary exploded perspective view showing thepreferred embodiment of a structural interconnection;

FIG. 10 is a cross-sectional view, taken along line 10—10 of FIG. 2,showing a second member employed with the preferred embodiment node; and

FIG. 11 is a fragmentary perspective view showing the preferredembodiment structural interconnection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description of the preferred embodiment is merelyexemplary in nature and is no way intended to limit the invention, itsapplication, or uses. For example, the apparatus and techniquesdisclosed herein may have utility in forming a wide variety of differentstructures including boats, bicycles, aircraft and railroad structures.

Referring to FIGS. 1 and 2, an exemplary structural interconnection 10includes a hydroformed node 12 constructed in accordance with theteachings of the preferred embodiment of the present invention.Hydroformed node 12 is shown operatively associated with an exemplaryvehicle frame 14. It should be appreciated that one or more of theinterconnections within vehicle frame 14 may include a hydroformed nodesuch as node 12 and the specific interconnection discussed hereinafteris an example thereof.

Vehicle frame 14 includes a pair of side rail panel panels 16 extendingsubstantially parallel to a longitudinal or fore-and-aft axis of thevehicle. A header panel 18 transversely spans vehicle frame 14 andinterconnects each of the side rail panel panels 16. Each of the panels16 and 18 are preferably constructed from an aluminum alloy exhibitinghigh strength per unit weight.

With specific reference to FIG. 2, side rail panel 16 is preferably agenerally hollow tubular shaped extrusion 20 having a first open end 22,a second open end 24 with at least one of nodes 12 positionedtherebetween. Side rail panel 16 also includes an outer surface 26 andan inner surface 28 defining a wall 30. The cross sectional shape of theside rail panel 16 may be alternately constructed to suit a variety ofdifferent design applications. It is feasible to implement an extrusionhaving a first wall thickness for an application requiring moderatestructural properties while another extrusion, having the same outersurface configuration as the first, may be formed to include a greaterwall thickness and correspondingly superior structural properties. Inthis manner, it is possible to implement the lighter weight extrusionhaving a thinner wall in an otherwise rigidly framed vehicle such as acoupe while the second stiffer member is more suitable for a convertibleautomobile application. By maintaining a common outer surface profile, asingle hydroforming die can create both coupe and convertible structuralcomponents as will be described hereinafter.

FIGS. 3 and 4 show two embodiments of pre-hydroformed extrusions. Anexemplary first extrusion 31, not incorporated within vehicle frame 12,includes an inner surface 32, an outer surface 33 and a flange 34integrally formed with and radially protruding from the outer surface33. The single flange or first extrusion 31 is contemplated for use as aheader panel with the flange 34 providing a mounting surface for awindshield. FIG. 4 shows a second extrusion 35 including a pair offlanges 36 radially extending from an outer surface 38. The dual flangeor second extrusion 35 of FIG. 4 provides mounting locations for othercomponents such as vehicle body panels. It should be appreciated thatthe outer surface 38 is varied by simply modifying the geometry of theextrusion die (not shown). Accordingly, features such as the mountingflanges 34 and 36 are integrally formed with the tubular member duringthe extrusion process.

Referring to FIG. 5, the preferred embodiment of the side rail panel 16is hydroformed from a third extrusion 40 including a generally constantthickness wall portion 42 and a reinforced thicker portion 44. Thereinforced wall portion 44 intrudes for approximately 30 to 45 degreesof the inner surface 28 of the side rail panel 16 obtaining a maximumthickness of approximately four milimeters. The generally constantthickness wall portion 42 is preferably one milimeter thick. It shouldbe appreciated that the reinforced portion 44 acts as a sump or well ofmaterial when forming the node 12 such that a suitable minimum wallthickness is maintained throughout the finished hydroformed node.Because the reinforced portion is structurally necessary only at nodelocations, it is advantageous to maintain the generally constant wallthickness portion 42 for the majority of the cross section therebyreducing the overall weight of side rail panel 16. Further weightreduction may be accomplished by selectively removing material locatedin the reinforced wall portions spaced apart from nodes 12.

As mentioned earlier, node 12 of the present invention is integrallyformed with side rail panel 16 through the use of internal fluidpressure, preferably by use of a hydroforming process. Hydroforming isessentially the process of deforming a tubular member to a desiredcomplex tubular shape. To this end and with reference to FIG. 6, atubular member such as extrusion 40 is placed between a first die 46 anda second die 48 having cavities 50 and 52 respectfully, which define thedesired resultant shape of the side rail panel 16. First end 22 andsecond end 24 of the tubular member are accessible through the dies anda seal (not shown) is connected to the ends of the tubular member.Pressurized fluid 54, typically water, is then injected into the ends ofthe extrusion 40 at a pressure of approximately 100,000 PSI, therebyforcing wall 30 to outwardly expand and conform to the internal shapedefined by the die cavities. Depending on the material chosen and thedepth of draw required, a number of intermediate hydroforming dies maybe required to assure uniform deformation of the side rail panel 16without rupture. For example, and in reference to FIG. 7, a third die 56and a fourth die 58 comprise a second hydroforming die set 60 forincrementally deforming the partially hydroformed extrusion 40 into thefinal desired shape. It should also be appreciated that, as mentionedearlier, the side rail panel 16 may be extruded to include other innerand outer contours prior to hydroforming to structurally enhance theside rail panel 16 and/or ease formation of the node 12.

With reference to FIGS. 8 and 9, the completed hydroformed node 12includes an end wall 62 and a side wall 64 extending substantiallyorthogonally from a longitudinal axis 66 of the side rail panel 16. Sidewall 64 is preferably formed at a small draft angle 68 typically rangingfrom three to seven degrees to facilitate removal of side rail panel 16from the dies after hydroforming. Side wall 64 includes a generallyconvex portion 70, and a generally concave portion 72 to form anasymmetric shape when viewed from the end wall 62. The shape of sidewall 64 functions to restrain header panel 18 from rotating onceinterconnected with node 12. As best shown in FIG. 8, side wall 64tapers, decreasing in thickness as the side wall approaches the end wall62 where the section is at a minimum.

With reference to FIGS. 9 and 10, header panel 18 is also a generallycylindrical hollow extrusion having a first open end 74 and a secondopen end 76. In the preferred embodiment each of the ends 74 and 76 arecoupled to a node 12 of the present invention. For clarity, only onesuch interconnection will be described in detail. Specifically, firstopen end 74 includes an inner surface 77 and an outer surface 78defining a wall 80. The wall 80 includes a first recess 82 and a secondrecess 84 shaped to compliment the outer surface 26 of the side railpanel 16. In addition, the first open end 74 includes a flared or swagedportion 86 for receipt of the hydroformed node 12.

Because the preferred header panel 18 is a tubular member, the flaredportion 86 may be created via a hydroforming process as well. In thismanner, the flared portion 86 may be accurately formed to provide a slipor interference fit with the hydroformed node 12 as desired. Preferably,the inner surface 77 of the flared portion 86 compliments the draftangle 68 formed by the side wall 64 of the node 12 such that the innersurface 77 is positioned adjacent the side wall 64 at assembly. Itshould also be appreciated that the tubular header panel 18 is merelyexemplary and that a variety of mating components may be utilizedincluding stampings and/or castings. Optimally, the stamping or castingwould include a flared portion to compliment the draft angle of thehydroformed node 12.

Reference should now be made to FIG. 11 wherein the structuralinterconnection 10 is completed by engaging node 12 of side rail panel16 with flared portion 86 of header panel 18. Header panel 18 ismechanically attached to side rail panel 16 to provide furtherstructural benefit. It is envisioned that a variety of attachmentmethods may be utilized including welding, mechanical fasteners,including rivets or screws, and adhesives. The preferred embodimentincorporates a plurality of rivets 88 extending through apertures (notshown) formed in the flared portion 86 of the header panel 18 and theside wall 64 of the hydroformed node 12. The apertures may be createdduring the hydroforming process or added subsequently by processes suchas drilling, stamping or laser cutting.

Therefore, it should be appreciated that the configuration and operationof the structural interconnection including a hydroformed node providesmanufacturing and operational advantages over the prior art.Specifically, the hydroformed node 12 of the present invention providesan integrally formed attachment location economically created throughthe use of hydroforming.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. While various materials have beendisclosed, it should be appreciated that a variety of other materialscan be employed. It is intended by the following claims to cover theseand any other departures from the disclosed embodiments which fallwithin the true spirit of this invention.

What is claimed:
 1. A vehicle frame comprising: a first member having agenerally hollow body with a first end, a second end, an outer surfaceand an inner surface, the first member further having a closed nodeportion protruding relative to a longitudinal axis defined by the body,the node portion being positioned between the first and second ends; anda second member having an aperture shaped to substantially match theshape of the node portion, wherein the node portion is placed in theaperture and the second member is coupled to the node portion.
 2. Theframe of claim 1 wherein the node portion includes a side wall and anend wall, the side wall protruding substantially orthogonally from thelongitudinal axis defined by the body.
 3. The frame of claim 2 whereinthe side wall has a convexedly shaped first portion and a concavedlyshaped second portion to orient the second member relative to the firstmember.
 4. The frame of claim 3 wherein the side wall protrudes from thebody at a draft angle.
 5. The frame of claim 4 wherein the second memberincludes a hollow body having a flared portion defining the aperture,the flared portion complimenting the draft angle.
 6. The frame of claim1 wherein the body includes a reinforced portion having an increasedwall thickness.
 7. The frame of claim 6 wherein the reinforced portionis positioned proximate the node portion.
 8. The frame of claim 7wherein the body is an extrusion.
 9. The frame of claim 8 wherein thebody further includes a flange radially protruding therefrom.
 10. Avehicle frame comprising: a first member having a generally hollow bodywith a first end, a second end, an outer surface and an inner surface,the first member further having a node integrally formed with andprotruding from the outer surface, the node being positioned between thefirst and second ends; and a second member having an aperture shaped tosubstantially match the shape of the node, wherein the node is placed inthe aperture and the second member is coupled to the node, wherein theside wall has a convexedly shaped first portion and a concavedly shapedsecond portion to orient the second member relative to the first member.11. The frame of claim 10 wherein the side wall protrudes from the bodyat a draft angle.
 12. The frame of claim 11 wherein the second memberincludes a hollow body having a flared portion defining the aperture,the flared portion complimenting the draft angle.
 13. The frame of claim10 wherein the body includes a flange radially protruding therefrom. 14.A vehicle frame comprising: a first member having a generally tubularbody defining a first wall portion and a second wall portion, whereinthe second wall portion is substantially thicker than the first wallportion, the first member further having a node portion protruding fromthe second wall portion of the generally hollow body; and a secondmember having an aperture to receive the node portion, wherein the nodeportion is positioned in the aperture and the second member is coupledto the node portion.
 15. The vehicle frame of claim 14 wherein the firstmember includes a substantially uninterrupted inner surface extendingthroughout the tubular body and the node portion.
 16. The vehicle frameof claim 15 wherein the node portion includes a side wall and an endwall, the side wall protruding substantially orthogonally from alongitudinal axis defined by the tubular body.
 17. The vehicle frame ofclaim 16 wherein the side wall has a convexedly shaped first portion anda concavedly shaped second portion to orient the second member relativeto the first member.